EEMCO Guidance to the in vivo Assessment of Tensile Functional Properties of the Skin

Abstract

Tensile functions of the skin and subcutaneous tissues contribute to the appearance of the aged and photodamaged skin and to the effects of various other pathophysiological processes. The assessment of tensile functions of skin can be performed by distinct approaches mainly characterized by the orientation and magnitude of the imposed stress and strain over time. Testing methods are basically grouped into five major classes which include tensile, torsional, indentation, impact and elevation modes. Computed tensile variables are reproducible when the experimental procedure occurs under fully controlled conditions. Consistent and relevant information is yielded when the limitations and pitfalls typical for each test method are taken into consideration.

Tissue elasticity and the ageing elastic fibre

“…In severely photoaged skin, however, abundant deposits of highly disorganised, elastic fibre material are distributed throughout the dermis (Warren et al 1991;Watson et al 2001;Werth et al 1996;Yaar and Gilchrest 2007) Early attempts to quantify the effects of ageing on the mechanical properties of skin were hampered by: the use of terminology which was open to misinterpretation (Doubal and Klemera 2002), the diversity of both mechanical tests (Diridollou et al 1998;Rodrigues 2001) and anatomical sites (Escoffier et al 1989), and most importantly by the heterogeneity and anisotropy of the skin layers themselves (Diridollou et al 1998;Pierard 1999). The mechanical response of skin to the application of tensile and torsional forces and to deformations induced by indentation and suction have all been reported in the literature (see Rodrigues 2001 for an excellent review). Of these techniques, torsional approaches, which may be used in vivo, have the advantage of applying mechanical stresses parallel to the plane of the skin, thereby minimising the influence of tissue anisotropy and underlying tissue structures on the measured mechanical parameters (Escoffier et al 1989).…”

“…Suction methods which use a negative pressure to deform the skin (Fig. 4c) are perhaps the most widely used (Diridollou et al 1999;Pierard 1999;Rodrigues 2001;Smalls et al 2006;Takema and Imokawa 1998;Takema et al 1994). Diridollou and co-workers suggest that this technique enables the measurement of mechanical responses which originate primarily from the dermis rather than subcutaneous structures (Diridollou et al 1998).…”

“…Applying either suction or torsional forces to skin induces a rapid elastic deformation (U E ), followed by a slower viscoelastic deformation (U V ) until finally the total skin deformation (U F ) is reached (Fig. 4d, e) (Escoffier et al 1989;Leveque et al 1980;Rodrigues 2001;Takema et al 1994). Removing the force allows the skin to recover and the ratio of the recovery to initial deformation quantifies the ability of the skin to elastically recoil.…”

“…Removing the force allows the skin to recover and the ratio of the recovery to initial deformation quantifies the ability of the skin to elastically recoil. Both the ratio of the rapid elastic recovery to the elastic deformation (where U R /U E is defined as the elastic function) and the ratio of the rapid elastic recovery to the total skin deformation (where U R /U F is defined as relative elastic recovery) have been quoted in the literature (Escoffier et al 1989;Rodrigues 2001;Smalls et al 2006). The ability of skin to recoil is significantly reduced by both the intrinsic (Escoffier et al 1989;Smalls et al 2006;Takema et al 1994) and extrinsic ageing processes Smalls et al 2006;Staloff et al 2008;Takema et al 1994) and by exposure to UV-A and UV-B radiation in vitro (Takema and Imokawa 1998).…”

Gynecologic and obstetric impact of the ehlers-danlos syndrome : clues from scrutinizing dermal ultrastructural alterations

“…The combination of clinical assessments and family history probably discloses only a minority of EDS patients. Measurements of the mechanical properties of skin [1][2][3] and dermal histopathology disclose more EDS subjects with moderate skin changes exhibiting or not degenerative joint alterations.…”